JPH11112845A - Electronic still camera - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To enable use of a strobe device without increasing a charging time while monitoring a moving image with an electronic viewfinder without increasing a load on a power supply. A monitoring device that consumes a large amount of power is turned off during a period of charging a main capacitor of a strobe device. After the charging of the main capacitor of the strobe device is completed, the monitor device is turned on. The timing for starting the charging of the main capacitor of the strobe device is preferably immediately after the power switch is turned on or after the recording operation by the recording unit is completed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic still camera, and more particularly, to an electronic still camera having a monitor device and a strobe device capable of displaying a subject image based on an image signal obtained through an image pickup means.

[0002]

2. Description of the Related Art Some conventional electronic still cameras include an optical viewfinder or an electronic viewfinder (LCD, EVF) and a strobe device as means for visually observing an object. This type of electronic still camera consumes a large amount of current while displaying a moving image on an electronic viewfinder such as an LCD, and also consumes a large amount of current when charging a main capacitor of a strobe device.

Therefore, if both are used at the same time, the burden on the power source is large, and the capacity of the power source must be increased, which causes a problem that the shape and weight of the power source increase. On the other hand, when displaying a moving image on an electronic viewfinder such as an LCD, there is a camera configured to prohibit the use of a strobe device. There is a problem that the device is useless.

In order to solve this problem, a proposal has been made to reduce the flash charging current relatively when it is necessary to supply power to a device other than a flash device such as an LCD (Japanese Patent Laid-Open No. 7-1995). 193773).

[0005]

However, when the strobe charging current is relatively reduced as described above, the charging time becomes longer, and a means for controlling the charging current is required. There is a problem of disadvantage. The present invention has been made in view of such circumstances, and it is possible to use a strobe device without increasing a charging time while monitoring a moving image with an electronic viewfinder without increasing a load on a power supply. It is an object of the present invention to provide an electronic still camera capable of performing the same.

[0006]

In order to achieve the above object, the present invention provides an image pickup means for picking up an image of a subject and converting the image into an image signal indicating the subject, and an image of the subject based on the image signal obtained by the image pickup means. A monitor device capable of displaying, a strobe device, a recording device that records an image signal obtained by the imaging device on a recording medium based on an operation of a release button, and a charging period of a main capacitor of the strobe device, Control means for turning off the monitor device.

That is, during the period of charging the main capacitor of the strobe device, the monitor device having large power consumption is turned on.
Change to F. Then, after charging of the main capacitor of the strobe device is completed, the monitor device is turned ON. As described in claim 3 of the present application, after the charging of the main capacitor of the strobe device is completed, the monitor device is turned on only when the monitor display switch is turned on.
When the monitor display switch is turned off, the monitor device is maintained in the OFF state even after the charging of the main capacitor of the strobe device is completed. In this case,
An optical viewfinder that allows the subject to be seen even when the monitor device is off is used.

Further, the timing for starting the charging of the main capacitor of the strobe device may be immediately after the power switch is turned on as described in claim 4 of the present invention, or the recording operation by the recording means as described in claim 5 of the present invention. After the end.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of an electronic still camera according to the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a perspective view showing an embodiment of an electronic still camera according to the present invention. As shown in FIG. 1, a front cabinet 10 and a rear cabinet 12 of the electronic still camera are
A lens / finder unit is formed on the right side of FIG. 1 so that the lens / finder unit can be housed. A grip is formed on the left side of the front cabinet 10 and the rear cabinet 12, and a memory card (smart media) 14 is attached and detached. It is formed to be possible.

The front cabinet 10 has a release button 16, a finder window 18, a light control sensor and a self-
An ED window 20, a strobe cover 22, and the like are provided, and a power switch 24, a mode dial 26, a liquid crystal monitor 28, and the like are provided in the rear cabinet 12. 29 is a jack cover. FIG. 2 is a block diagram showing the internal structure of the electronic still camera.

This electronic still camera includes a lens / finder unit 30, a CCD image pickup unit 40, a main processing unit 50, a recording medium / LCD control unit 70, a throttling device 80, a switch unit 85, a jack unit 90, and a power supply unit 97. It is configured. The lens / finder unit 30 includes a photographing lens 32, an optical viewfinder 34, an aperture device (not shown), and driving means for these.
Note that the taking lens 32 and the optical viewfinder 34
Tele / wide switching is simultaneously performed by the driving force from one zoom motor, and the aperture device moves the aperture plate provided with an aperture to move the aperture stop (F2.4) and small aperture. The aperture can be switched between two stages of the aperture (F6.7).
Further, the focus lens of the photographing lens 32 can be moved by the focus motor.

The CCD image pickup unit 40 includes a solid-state image pickup device (CC
D) The subject light formed on the light receiving surface of the CCD 42 via the photographing lens 32 and the aperture device, including the CCD drive circuit 44, is converted into a signal charge corresponding to the amount of incident light by each sensor. Is converted. The signal charge thus accumulated is read out to the shift register by a read gate pulse applied from the CCD drive circuit 44, and is sequentially read out as a voltage signal (image signal) corresponding to the signal charge by the register transfer pulse. The CCD 42 has
A shutter drain is provided via a shutter gate. By driving the shutter gate with a shutter gate pulse, accumulated signal charges can be swept out to the shutter drain. That is, this CCD 42
Has a so-called electronic shutter function of controlling the accumulation time (shutter speed) of the electric charge accumulated in each sensor by the shutter gate pulse. Further, the CCD drive circuit 44 outputs various pulse signals to the CCD 42 based on a synchronization signal applied from the timing signal generation circuit 55 and a signal related to the electronic shutter control value.

The main processing unit 50 mainly includes a CDS circuit 51, a digital signal processing circuit 52, and a compression / decompression circuit 5.
3, frame memory 54, timing signal generation circuit 5
5. It is composed of a microcomputer 56 and the like. CDS circuit 5
Reference numeral 1 denotes a CDS clamp 51A, a gain control amplifier 51B, and an A / D converter 51C. The image signal read from the CCD 42 is sampled and held by the CDS clamp 51A for each pixel.
After being amplified by the gain control amplifier 51B, A
The signal is converted into an R, G, B point-sequential digital signal by a / D converter 51C and is applied to a digital signal processing circuit 52. The gain of the gain control amplifier 51B is controlled by a not-shown electronic volume.

The digital signal processing circuit 52 includes R, G, B
A multiplying circuit for independently multiplying the signal by an amplification control value; a circuit for calculating a color integrated value by integrating the R, G, B signals for each color; a color difference signal BY, R- based on the R, G, B signals
Y, a circuit for generating a luminance signal Y, a luminance signal Y for one screen
And a photometric circuit for calculating the integrated value (photometric value), and determines the amplification control values of the R and B signals based on the color integrated value, thereby performing white balance control.

The digital signal processing circuit 52 exchanges the luminance signal Y and the chroma signal C with the compression / decompression circuit 53, and converts the color difference signals BY, RY and the luminance signal Y into D / D signals.
The luminance signal Y is output to an A converter 57 to an autofocus (AF) AF evaluation circuit 58, and the photometric value is output to a microcomputer 56. The compression / expansion circuit 53 includes a memory controller of the frame memory 54, compresses the luminance signal Y and chroma signal C for one frame stored in the frame memory 54 in a predetermined format, and stores the compressed image data in a recording medium. It outputs to the recording media controller 72 of the / LCD control unit 70, and decompresses the compressed image data from the recording media controller 72 and stores it in the frame memory 54.

The AF evaluation circuit 58 comprises a high-pass filter for extracting the high-frequency component of the luminance signal Y and an integrating counter for integrating the extracted high-frequency component for one screen. It is output to the microcomputer 56 as an AF evaluation value. The microcomputer 56 performs overall control of each circuit based on a switch operation of the switch unit 85, and based on the photometric value, the aperture value of the aperture device and the C value.
The electronic shutter control value of the CD 42 is determined, the aperture device is controlled via the aperture / zoom drive circuit 60, and the timing signal generation circuit 5 is controlled based on the electronic shutter control value.
5. A shutter gate pulse is applied to the CCD 42 via the CCD drive circuit 44 to control the charge accumulation time in the CCD 42.

The microcomputer 56 includes an AF evaluation circuit 58
The focus lens is moved via the AF drive circuit 61 so that the AF evaluation value becomes the maximum based on the AF evaluation value added from the step (a), and focusing is performed. When the focus lens is at the in-focus position, the high frequency component in the image signal is the largest, and the AF evaluation value is the largest. Furthermore,
The microcomputer 56 turns on the liquid crystal monitor 28 as described later.
/ OFF and the strobe device 80 are controlled.

On the other hand, the digital signal processing circuit 52
The color difference signals BY, RY, and the luminance signal Y converted into analog signals via the A converter 57 are applied to a mix circuit 63 via a low-pass filter 62. The other input of the mix circuit 63 includes a character generator 6
4 mixes these signals, and the mix circuit 63 mixes these signals to control the LC of the encoder 65 and the recording medium / LCD control unit 70.
It outputs to the D drive circuit 74.

The encoder 65 receives an input color difference signal B-
For example, based on the Y, RY, and luminance signals Y, a color composite video signal of the NTSC system is generated, and this is output to the jack unit 90.
Is output to the video output terminal 96. The LCD drive circuit 74 drives the liquid crystal monitor 28 based on the input color difference signals BY, RY, and luminance signal Y, and displays an image on the monitor screen.

The recording medium controller 72 of the recording medium / LCD control section 70 records the image data compressed by the compression / decompression circuit 53 on the memory card 14 mounted on the socket 76.
The image data recorded in the memory is read out and a compression / decompression circuit 5 is read out.
Output to 3. The throttle device 80 is, for example, an auto flash device capable of automatically emitting low-luminance light, and mainly includes a flash control circuit 81, a main capacitor 82, a discharge tube 83,
It is composed of a light control sensor. When the subject brightness is equal to or lower than the predetermined brightness (in this embodiment, the shutter speed is set to 1 /
If the time is less than 100 seconds), strobe light emission is performed.
That is, when the microcomputer 56 determines that flash photography is to be performed based on the photometric value, the microcomputer 56 outputs a flash emission command to the flash control circuit 81 based on the operation of the release button 16, and the flash control circuit 81 Outputs a trigger signal for causing the discharge tube 83 to emit strobe light, and supplies the electric energy stored in the capacitor 82 to the discharge tube 83. Also, a flash control circuit 81
When the amount of light received by the dimming sensor 84 that receives the reflected light from the subject reaches a predetermined amount, the electric energy to the discharge tube 83 is cut off and the strobe light emission is stopped. Note that the strobe device 80 can emit light not only when the luminance is low but also when the forced light emission button is turned on.

The switch section 85 is provided with a tele / wide zoom switch 86, a +/- key, an execution key 87, a monitor display switch 88, and the like, in addition to the release button 16, the power switch 24, and the mode dial 26 described above. Have been. The release button 16 is turned on when the release button 16 is half-pressed, and is turned on when the release button 16 is fully pressed.
And a switch S2. The mode dial 26 can select photographing, playback, erasing, a self-timer, and the like. Further, the monitor display switch 88
This is a switch for turning on / off the liquid crystal monitor 28.

The jack section 90 includes a buzzer 91 for generating a shutter sound and a warning sound, an RS232C interface 92 and its serial terminal 93, a capacitor 94 for date backup, a power input terminal 95 for an AC adapter,
And a video output terminal 96. Power supply unit 97
Includes a DC / DC converter, and the jack 90
Power is supplied from a power input terminal 95 or a battery 98, and power of an appropriate voltage is supplied to each circuit in the camera.

Next, the control operation according to the present invention will be described with reference to FIG.
This will be described with reference to the flowchart of FIG. FIG. 3 is a flowchart showing a control operation when the power switch 24 is turned on. As shown in FIG.
6, when the power switch 24 is turned on (step S
10), charging of the main capacitor 82 is started immediately via the flash control circuit 81 of the flash device 80 (step S12). Then, it is determined whether or not the charging of the main capacitor 82 has been completed (step S14), and when the charging has been completed, the main capacitor 82 is put into a sleep state (step S16).
In this sleep state, various switch inputs can be received, but power is not supplied to the imaging circuit system,
Of course, the liquid crystal monitor 28 is also turned off, thereby suppressing power consumption.

In the sleep state, it is determined whether or not the monitor display switch 88 has been turned on (step S1).
8) When the monitor display switch 88 is turned on, power is supplied to the imaging circuit system and the liquid crystal monitor 28 is turned on.
(Step S20). Thereby, the liquid crystal monitor 2
8 displays a subject image (moving image) (step S2).
2).

As described above, when the power switch 24 is turned on, the main condenser 8 of the strobe device 80 is immediately turned on.
2 is charged, and then the display on the liquid crystal monitor 28 is enabled. Therefore, after the power switch 24 is turned on,
Until the main capacitor 82 is charged, the liquid crystal monitor 28 remains off regardless of the operation of the monitor display switch 88.
F, the supply of power to the liquid crystal monitor 28 is prohibited.

FIG. 4 is a flowchart showing a control operation when the release button 16 is operated in a movie state for displaying a moving image. That is, step S30 indicates a movie state in which the liquid crystal monitor 28 is turned on and the subject image (moving image) is displayed on the liquid crystal monitor 28. In this state, the switch S1 is turned on (the release button 16
Is determined (step S3).
2).

When the switch S1 is turned on, the aperture value of the aperture device and the CC value are determined based on the photometric value obtained by the photometric circuit.
The electronic shutter control value of D42 is determined, and the diaphragm device and C
The charge accumulation time in the CD 42 is controlled, and the AF evaluation value obtained by the AF evaluation circuit 58 is used to control the AF.
The focus lens is moved so that the evaluation value becomes maximum, and focusing is performed (step S34).

Subsequently, it is determined whether or not the switch S2 has been turned ON (the release button 16 has been fully pressed) (step S36). When the switch S2 is turned on, exposure for recording and reading of image data are performed by a togger signal of the switch S2, compression processing of the image data by the compression / decompression circuit 53, and recording of the compressed image data. Memory card 14 by media controller 72
Is performed (step S38).

When the recording process is completed, the liquid crystal monitor 2
8 is turned off (step S40). Subsequently, charging of the main capacitor 82 of the strobe device 80 is started (step S42), and it is determined whether or not charging of the main capacitor 82 is completed (step S44).
When the charging is completed, the liquid crystal monitor 28 is turned on again.
(Step S46), and set to a movie state for displaying a moving image on the liquid crystal monitor 28 (step S48).

As described above, when the release button 16 is operated in a movie state in which a moving image is displayed on the liquid crystal monitor 28, after the shooting and recording are completed, the liquid crystal monitor 28 is temporarily turned off and the liquid crystal monitor is turned off. The supply of power to the flash device 28 is prohibited, and the main capacitor 82 of the strobe device 80 is charged during that time.
Is turned on to display a moving image.

In this embodiment, the electronic still camera provided with the monitor display switch and the optical viewfinder has been described. However, the present invention is not limited to this, and the electronic still camera not provided with the monitor display switch and the optical viewfinder is not limited thereto. The present invention can be applied to a camera.

[0032]

As described above, according to the present invention, the monitor device which consumes a large amount of power is turned off during the charging period of the main capacitor of the strobe device, so that the load on the power supply is increased. Instead, it is also possible to shoot using a strobe device while monitoring a moving image with a monitor device. Also, by turning off the monitor device, the full power of the camera power supply can be used for flash charging, and the charging operation can be completed quickly. Furthermore, it can be dealt with only by changing the software of the existing electronic still camera, which is advantageous in terms of cost.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of an electronic still camera according to the present invention.

FIG. 2 is a block diagram showing an internal structure of the electronic still camera shown in FIG.

FIG. 3 is a flowchart showing a control operation when a power switch is turned on.

FIG. 4 is a flowchart showing a control operation when a release button is operated in a movie state for displaying a moving image.

[Explanation of symbols]

 14 Memory card (smart media) 16 Release button 24 Power switch 28 Liquid crystal monitor 32 Photographing lens 34 Optical viewfinder 42 Solid-state image sensor (CCD) 52 Digital signal processing circuit 53 Compression / expansion circuit 54 ... Frame memory 56 ... Microcomputer 74 ... LCD drive circuit 80 ... Throttle device 82 ... Main capacitor 88 ... Monitor display switch

Claims (5)

[Claims] An imaging unit configured to image a subject and convert the image signal into an image signal indicating the subject; a monitor device capable of displaying a subject image based on the image signal obtained by the imaging unit; a strobe device; Recording means for recording an image signal obtained by the imaging means on a recording medium based on the operation of, and during a period of charging the main capacitor of the strobe device,
An electronic still camera, comprising: control means for turning off the monitor device. 2. The control device turns on the monitor device after charging of a main capacitor of the strobe device is completed.
The electronic still camera according to claim 1, wherein And a monitor display switch for turning on / off the monitor device, and an optical viewfinder that allows a subject to be viewed even when the monitor device is turned off, wherein the control unit charges a main capacitor of the strobe device. 2. The electronic still camera according to claim 1, wherein the monitor device is turned on only when the monitor display switch is turned on after the completion. 4. The control device has a power switch turned on.
2. The electronic still camera according to claim 1, wherein charging of the main capacitor of the strobe device is started immediately after the electronic device is operated. 5. The electronic still camera according to claim 1, wherein the control device starts charging a main capacitor of the strobe device after a recording operation by the recording unit is completed.